Basing of radio tubes and the like



May 17, 1949. M. J. @RR 2,470,518

'BASING OF RADIO TUBES AND THE LIKE Filed Nov. 20, 1946 JNVENroR. Mart J rr Kwam# Patented May 17, 1949 BASING OF RADIO TUBES AND THE LIKE Mark J. Orr, Emporium, Pa., assigner to Sylvania Electric Products, Inc., a corporation of Massachusetts Application November 20, 1946, Serial No. 711,106

6 Claims.

This invention relates to radio tubes and the like.

It has heretofore been a standard practice in completing radio tubes and like devices to attach a, cupped base, usually of a molded insulating plastic and carrying tubular metal pins, to a glass envelope having flexible metal leads projecting externally from the electrodes Within the envelope. A basing cement has been used to secure the glass envelope rigidly to the base. According to that procedure the interior wall of the base is coated with basing cement as a preliminary operation. Then the projecting leads are threaded through the metal tubes of the base, and with the base pressed firmly into contact with the glass envelope, the assembly is heated to form the envelope-to-base seal. The metal leads, projecting beyond the tubular pins, are trimmed even with the tube-ends and soldered thereto to complete the basing operation.

It is an object of the present invention to simplify this process of basing of radio tubes and similar plug in devices. A further object is to devise a novel basing method that is effective yet economical. Another object is to provide new forms of envelope and base which can be assembled without basing cement. The application of cement to the base and the heating of the cement to form the seal are both operations which are eliminated, in the practice of my invention.

In practicing this invention, a plurality of interengaging projections and recesses are provided on the base and on the envelope which prevent mutual rotation about a common axis. In the preferred form of the invention the projections are on the glass envelope in the form of a collar surrounding each of the metal leads, thereby extending the effective length of seal between the glass envelope and each of the leads. For receiving these projections the base is formed with plural cavities adjacent the inner extremities of the usual metal tubes into which the leads are to be threaded and soldered. The interengaging projections and cavities prevent mutual rotation of the base and the glass envelope, thereby establishing the desired envelope-to-base attachment without resort to a cement, The side wall of the base acts further to inhibit relative movement of envelope and base.

The invention, together with further objects and features thereof, will be better understood from the following detailed disclosure of a preferred specific embodiment thereof which is shown in the drawings.

Fig. 1 is a lateral elevation of a radio tube complete with envelope and base Fig. 2 is a schematic view of the envelope projections (shown in section) within the recesses of the base;

Fig. 3 is a vertical section through the base, showing the glass envelope and leads as in the preferred form of completed and based radio tube;

Fig. 4 is a. bottom view of the novel envelope with its leads, in this instance the envelope being wholly of glass;

Fig. 5 is a plan View of a novel base adapted for assembly with the envelope of Fig. 4.

In the radio tube of Fig. 1 glass envelope Ill is assembled to base l2 from which pins lll project. These are to establish connection with a socket (not shown) into which the tube may be plugged. Base l2 includes a central projection I6 having a key IB which insures proper orientation of the tube in its socket, so that pins Il! will contact the correct socket terminals.

In the for-m shown envelope l0 has eight axially extending leads 22. Each lead optionally includes a rod .22a to the end of which there is buttwelded a more flexible lead 22h. Portion 22a is of a metal having proper surface characteristics for forming a good metal-to-glass seal and has the same, or nearly the same, coeicient of thermal expansion as that of the glass in accordance with common practice. The composite lead is molded into a glass header which subsequently forms the lower end of the envelope, as a well known step in the manufacture of one form of completed envelope. In the present invention, however, each lead is surrounded by a collar 2E] which is formed as part of the header. These collars extend the glass-to-metal seal, when compared to a header of the same thickness which does not have such collars. Viewed otherwise, these collars make it possible to have the same length of glass-to-metal seal while permitting a reduction in the average thickness of the glass header to reduce the processing strains therein. In that type of envelope which is wholly of glass it is desirable to have a header of generally the same thickness as the wall of the remainder of the envelope, but the header must be sufficiently thick to provide the necessary length of glass-tonietal seal at each of the leads. The envelope l0 is also provided with the usual exhaust tubulation 2d, sealed off in advance of the basing step.

Base I2 of a molded plastic has an inner surface 26 which is somewhat flared, as shown, to facilitate molding. This surface is made only slightly larger in diameter than the envelope IE! so that a, close t is obtained. A press t that might crack the plastic is avoided. Tubular pins I4 are rigidly secured to base I2 in a circle, as in a Well known form of prior art base, but in this instance each pin I4 is attached at the bottom of a recess 28. Each recess is made deep enough toll accommodatie collarsi ZIfands the' flared or staked portion of pin I4. There' ison'e recess 28 for each collar '20; except that there is a special recess 28a made larger than the others (Figs 2 and 3) which is to receiveia'collar-"2911ilarger than the other collars 20. In the broader aspects of the invention, there maybefa larger number ofr collars and recesses than there` are metal; leads; the leads need not be central of the projections termed collars; `and there'fmay be'fewer/ pro'- jections than there are leads. The embodiment described is distinctly to be preferred, howeverl During the manufacture of the envelope according toknowrr'nfie'tlds, the 'elementswithin the envelope n1 '-beif'soc'o nested? -to leads 22 that they WilliI atelyf 'connected to' the proper pins I4; in relatiasfte locating key la Envelope I is provided with a small but readily noted projection 30lr (Figs 3- and; 4) When 'the elementsare assembled n a predeterminedrelationl to the various" leai'dsfthey will! be properly oriented with respect to key I8 if projections@l is in proper relation withethe base [2.- Projection 30 is formed adjacent-large"'collar Zilal.. Were collar a easily discerned fromftlie other collars 2li this'proj'ection would notf'bef necessary.

In base assembly' v'pefiation?, leads 22 are threaded through? tubesf W Withthelaid or' projection 3`0,"the lead of collar 20ct being thereby aligned with tubular: pini# in larger--itliari-aver age cavity 28d.Y Envelope- IU isthenrmly seated Withinl'lase I2?, ai-idat-tlistimef flexible portions 22oof`leads 22 would normally extendwell beyond the ends-of tubes Hf It would be readily apparent to the-assembler that thebaseA is not properly' assembled to envelope '='I Il, if suchv should be the case, since' ilarsecollar ZIIafWould not fit Within any recess 'arid-Would therefore prevent the envelope from firinl'yfseati-ng in the base.

Re'cesses 28are"'made slightly larger than collars 2`0,but because ofexpect'ed `deparumes from the ideal,- a'lW'dTIi-I' my tolerantie' specifi-Catio'ns', one or more" shoulders "286 may be relied upon to contact-"one walloffits recess 28 while one orinore shouldersciinay be vrelied upon to Contact the opposite Wall (inthe rotational direction) to assure rrrrinterengageinent between envelope l0` and base -lzfpreventing 'mutual rotation about the 'ain'sof the radio tube.

As is apparent/from Fg.w3 I'a clearance isprovided between rods'7`2d-'atid the'finternalbore of tubular pins -'|4. Any torsional stress that may be imposed betvveenenvelope llil and base I2 is thus taken up' bynprojections 2U 'within cavities 28, Without straining the metal'eto'eglass seals of the leads.

vEktelisions `22b` are trinimedlneatly atI the ends of tubes I 4, and, after application of soldering uur; to the e'nls of the tubes and of leads 22o, molten solder Y is allowed-tolse drawn 'up into the tubes'. These-solderedrjoints prevent the envelopefrom tippingone way or another within base I2. rfhe combined actionof' the soldered leads and the seated'collars is'such as to'pre'vent anymutual motion'bet'we'enthe l'ern'felopel and the base. The soldering operation is'conventional, except that in thevpresent basing'procedure it may be necessaryt utilizesorhevvliat more solder than in the the prior art where basing cement was relied upon to establish the rigid base-to-envelope seal. The preliminary operation of coating the base with cement and the later operation of cementing the envelope to the base are eliminated. Only a structural modication is necessitated in the mold for the base, and in the header mold? if it is not alreadyl shaped to.l form collars 2i! and 20a. The resulting economy that arises from the novel method and construction of parts Will be apparent, and a further assurance of proper assembly of the envelope within the base is had.

While the inventionhas been described in connection with radio tubes, it will be evident that it is equally applicable to a variety of other basing uses, as' irl lamps, cathode-ray tubes, and other devices Which are adapted to be plugged into a connector socket.

Having thus described-'a particular embodiment of my inventionand' explained its underlying principle, what I claim is:

1. A radio tube comprising avglass envelope having a generallyr flatl end, a plurality of metal leads extending through saidy flat end, a glass collar surrounding each off'offsaid leadsl and integral with said end, a base of insulating materia-l having a series oi cavities slightl-y'larger than said collars and arranged to receive the collars, and an upstanding tubular portion adapted to receive said glass envelope,` a plurality of metal tubes secured to said base, one tube in each of at least several oi said cavities and projecting from the opposite surfacev of the base, the bore of said tubes being larger than the maximum diameter of said leads, said leads being secured to said tubes at their ends remote from the end of said envelope, one of said collars being larger than others and one of saidcavities beingr larger than others to assure unique orientation of the base with respect to the envelope, and a central projection from said base having a circularly asymmetrical orientation portion.

2. A device adapted to be plugged into a socket and comprising an envelope having a generally at glass end and a cylindrical -portion adjacent said end, a plurality of integral projections on the external surface thereof, a metal lead eXn tending centrally through at least certain of said projections and sealed thereto, a base of insulating material having a series of cavities to receive said projections, and an upstanding tubular portion adapted to snugly receive the cylindrical portion of said envelope, a metal tube secured to said base at the bottom of those of the cavities which are to accommodate said metal leads, each lead being secured to its metal tube at a point remote from said envelope.

3. A device adapted to be plugged into a socket comprising an envelope having a cylindrical end portion, a plurality of flexible mutually insulated parallel metal leads extending through and sealed to said envelope at said end, a plurality of external, integral projections thereon, a base of insulating material having a series of parallel metal tubes to receivev said leads, and an upstanding tubular portion adapted to snugly receive the cylindrical portion of said envelope, and a series of cavities to receive said projections for inhibiting mutual surface-to-surface sliding of said envelope and said base, said leads being secured to said tubes at points remote from said envelope to prevent material separation of said envelope and to avoid stressing thev seals between said envelope and said leads.

4. A plug in device comprising an envelope having a cylindrical portion at one end, a plurality of mutually insulated metal leads extending through said envelope at said end, a base of insulating material having a series of metal tubes to receive said leads, said base having a tubular portion adapted to quickly receive the cylindrical portion of said envelope, and interengaging projections and cavities on said at end and on said base, respectively, for inhibiting relative movement of said envelope along a surface of said base, said leads being secured to said tubes to prevent mutual separation of said base and said envelope.

5. A device as described in claim 4, wherein said leads are flexible and, at their largest diameter, are smaller than the bore of said tubes.

6. A radio tube or like device comprising an envelope having a plurality of generally parallel projecting metal leads, a collar surrounding each of said leads and integral with said envelope, a base of insulating material having a series of cavities arranged to receive said collars and a REFERENCES CITED following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 20 2,080,837 Shrader May 18 1937 2,206,798 Woods July 2, 1940 2,383,925 West Aug. 28, 1945 

